Because many studies rely upon detergents to solubilize lipophilic agents such as cannabinoid drugs, we examined the effect of commonly employed detergents on the function of the cloned alpha(7) subunit of the nicotinic ACh receptor. Homomeric alpha(7) receptors were expressed in Xenopus oocytes and the two-microelectrode voltage-clamp technique was used to assess their electrophysiological properties. The detergents Tween 80 and Triton X-100 reversibly inhibited ACh (100 microM)-induced inward currents in a concentration-dependent manner, with IC(50) values of 610 nM and 1.4 microM, respectively. The effects of these detergents were independent of membrane potential, and they were not mediated by endogenous Ca(2+)-dependent Cl(-) channels, since they were unaffected by intracellularly injected BAPTA, and recorded in Ca(2+)-free bathing solution containing 2 mM Ba(2+). Both detergents also decreased the maximal effect of ACh, without significantly affecting its EC(50), indicating a non-competitive interaction with the nACh alpha(7) receptors. In contrast to the effects of these detergents, we found that cholic acid (10 microM), DMSO (10 microM) and Tocrisol (0.01% v/v) did not cause a significant effect on nicotinic responses. In conclusion, we demonstrate that the detergents Tween 80 and Triton X-100 are potent inhibitors of neuronal nACh alpha(7) receptors expressed in Xenopus oocytes, and we suggest that studies utilizing these detergents to solubilize lipophilic drugs should be scrutinized for such effects.